Conventionally, a semiconductor device includes a fuse circuit having electric fuses in order to set a redundancy circuit or adjust resistance values (see Japanese Laid-Open Patent Publication No. 2007-073576). The electric fuses are molten and broken due to supply of an overcurrent. The fuse circuit generates a signal that corresponds to the state of an electric fuse (unbroken state or conduction state having a low resistance value, or broken state or non-conduction state having a high resistance value).
In the electric fuse, it is difficult to sufficiently secure the insulating distance between ends of a molten portion, that is, distance between fuse conductors which are molten and separated from each other. If the insulating distance of the molten portion is not sufficient, there is a possibility that so-called glow-back may occur by which the value of resistance between two terminals of the electric fuse gradually decreases over time owing to, e.g., electromigration. This may change the molten portion of the electric fuse to the conduction state.